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MHT CET2016MathematicsVector Algebra

If a → = i ^ + j ^ + k ^ , b → = 2 i ^ + λ + k ^ , c → = i ^ − j ^ + 4 k ^ and a → . ( b → × c → ) = 10 , then λ is equal to

Options

  1. A6
  2. B7
  3. C9
  4. D10

Correct answer

A. 6

Step-by-step solution

1 1 1 2 λ 1 1 - 1 4 = 10 1 4 λ + 1 - 1 8 - 1 + 1 - 2 - λ = 10 ⇒ 4 λ + 1 - 7 - 2 - λ = 10 ⇒ 3 λ = 18 ⇒ λ = 6

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